The water drains more and more slowly, a strange smell comes up the plughole and, one day, the sink stays full. Before you call anyone out, it’s worth knowing how to unblock a kitchen sink with what you already have at home: in most cases, hot water, a plunger or opening up the U-bend is enough. Here are the home remedies to unblock a kitchen sink that work, and the order to try them in.
- Why kitchen sinks get blocked
- How to unblock a kitchen sink step by step
- No plunger? The U-bend and a drain snake
- If the sink is full of water
- Caustic soda and hydrochloric acid
- How to stop it blocking again
- Frequently asked questions
Why your kitchen sink gets blocked
Enemy number one is grease: cooking oil goes down as a liquid, cools in the pipe and sticks to the walls. Rice, coffee grounds and crumbs then cling to that layer until the water can barely get through. The good news is that almost all blockages are close by: in the plughole or in the U-bend, the curved section of pipe under the sink.
How to unblock a kitchen sink step by step
Work your way up: each method takes a little more effort than the last, but reaches further.
1. Very hot water and washing-up liquid
Heat a litre of water, add a good squirt of washing-up liquid and pour it slowly down the plughole. The heat softens the grease and the soap helps to wash it away. If your pipes are PVC, very hot is better than boiling. Repeat two or three times.
2. Bicarbonate of soda and vinegar
To unblock a kitchen sink with vinegar and bicarbonate of soda, pour half a glass of bicarb down the plughole, followed by a glass of vinegar. It will fizz: cover the plughole with a cloth or the plug and wait about 30 minutes. Finish with very hot water. It works well on minor blockages and for getting rid of smells; with a solid plug of grease, it usually falls short.
3. Plunger
Leave a few centimetres of water in the sink so the plunger can create suction. If you have a double sink, block the other plughole with a wet cloth. Push and pull hard about ten times without lifting the plunger off, then pull it away sharply.
| Method | Best for |
|---|---|
| Hot water and soap | Slow drainage caused by grease |
| Bicarb and vinegar | Minor blockages and bad smells |
| Plunger | Blockage near the plughole |
| Cleaning the U-bend | Built-up solid debris |
| Drain snake | Blockage beyond the U-bend |
How to unblock a kitchen sink without a plunger
If you don’t have a plunger, the most effective fix is under the sink. To clean the U-bend:
- Put a bucket underneath and keep a cloth handy.
- Unscrew the nuts on the U-bend (they’re usually plastic and can be undone by hand).
- Empty the debris into the bucket, wash the U-bend in hot water with an old brush and check the washers.
- Put it back together without overtightening and run the tap to check it doesn’t drip.
If the U-bend is clean and the water still won’t drain, the blockage is further along. That’s where a drain snake comes in: you feed it into the pipe by turning the handle until you feel resistance, then keep turning to break up or hook the blockage.
What to do if the sink is full of water
If the sink is full of water, don’t pour in any chemicals: they would splash you when you use the plunger. Bail the water out with a saucepan until there are just a few centimetres left and try the plunger. If that doesn’t work, empty the sink completely and move on to the U-bend.
Caustic soda and hydrochloric acid: handle with extreme care
Chemical drain unblockers are a last resort. If you use them, follow the instructions on the label, wear gloves and goggles, ventilate the room and don’t lean over the plughole. Two rules you must never break:
- Never mix products. Hydrochloric acid mixed with bleach gives off toxic gases. If you’ve already poured one in and the water won’t drain, don’t add anything else: call a plumber.
- Never use a plunger after a chemical product: the product can splash you.
What about Coca-Cola? Don’t expect miracles: on a plug of grease, it does little more than hot water.
How to stop your kitchen sink blocking again
- Don’t pour oil down the sink: let it cool in a jar and take it to your household recycling centre or your council’s cooking oil collection point.
- Fit a strainer in the plughole to catch rice, peelings and coffee grounds.
- Once a week, very hot water with washing-up liquid; once a month, bicarbonate of soda and vinegar.
If your dishwasher drains into the same U-bend, check its filter too: we explain how in how to clean a dishwasher. And if you’re after ideas to keep your home in good shape, have a look at Velia Select’s home products.
If the water still won’t go down, comes up through another plughole or the blockage keeps coming back every few days, the problem may be in the soil stack: that’s the time to call a plumber.
Frequently asked questions
What’s the best way to unblock a sink?
For most kitchen sinks, the most effective option is very hot water with washing-up liquid, followed by a plunger. If that’s not enough, cleaning the U-bend sorts out almost every case without chemicals.
How long should you leave bicarbonate of soda and vinegar to work?
About 30 minutes, with the plughole covered. Then rinse with very hot water. If the blockage is minor, you can repeat it.
Why does my kitchen sink drain smell?
Normally because of food scraps and grease rotting in the U-bend. Cleaning it and using bicarbonate of soda and vinegar every so often will usually get rid of the smell.